The invention relates to a tomographic x-ray apparatus for the production of transverse layer images of a radiography subject, comprising a patient support, a radiation measuring arrangement with an x-ray source which generates a beam of rays penetrating the radiography subject and whose cross-sectional extent perpendicular to the layer plane is equal to the layer thickness, and a radiation receiver which determines the radiation intensity behind the subject, comprising a driving device coupled with the measuring arrangement for effecting rotational movement thereof, comprising a measured value converter for conversion of the signals supplied by the radiation receiver into a layer image, and comprising means for locking the measuring arrangement against rotation during the processing of the measuring signals delivered by the radiation receiver.
For the production of transverse layer images, computer aided tomographic apparatus is known which exhibits a radiation measuring arrangement with which the transverse layer is scanned from different projections. From the output signals of the radiation receiver of the radiation measuring arrangement a computer calculates the image of the examined transverse layer.
In the case of specific x-ray-diagnostic examinations accompanied by the use of contrast agents, the physician requires quantitative information regarding the contrast agent concentration and its chronological travel path (or course, or progression), for example in larger blood vessels.